Three speed floating cup hydraulic motor

ABSTRACT

A hydraulic motor includes a rotor supporting a plurality of piston elements projecting away from opposing faces of the rotor. The rotor is adapted to rotate about a first axis. The hydraulic motor further includes a pair of drum plates each supporting a plurality of cup elements. The plurality of cup elements are adapted to engage the piston elements. Each drum plate is arranged on an opposing side of the rotor and is adapted to rotate about a second axis in angled relation to the first axis. Each of a pair of swashplates is in operative engagement with a respective one of the drum plates and each is adapted to pivot relative to the rotor to move with the respective drum plate between a maximum displacement position and a minimum displacement position to thereby change the angled relation between the first axis and the second axis. The pair of swashplates are further independently pivotable between three different settings.

TECHNICAL FIELD

This patent disclosure relates generally to hydraulic motors and, more particularly to floating cup hydraulic motors.

BACKGROUND

Hydraulic motors can be used to propel a variety of machines, e.g., loaders, excavators, dozers and the like. To provide two different operating speeds, the piston pumps in conventional hydraulic motors may use a simple toggle to switch a swashplate angle between maximum and minimum displacement settings. The maximum displacement setting may provide relatively low speed and high torque, while the minimum displacement setting may provide relatively high speed and low torque.

Conventional hydraulic motors utilize piston pumps with five, seven or nine pistons. As a result, starting torque of the motor can be quite low. Hydraulic motors utilizing a so-called floating cup type pump can provide higher initial starting torque than conventional hydraulic motors. A hydraulic motor based on a floating cup type pump is disclosed in International Patent Publication No. WO 2006/094990-A1 in the name of Achten, having a publication date of Sep. 14, 2006. The disclosed floating cup type pump generally utilizes a plurality of piston elements projecting away from either side of a rotor.

The pumps described in this reference include a centrally disposed rotor having a plurality of pistons projecting away from both sides of the rotor. A pair of cooperating drum plates disposed outboard from the rotor support an arrangement of cup elements or drum sleeves adapted to house distal portions of the pistons. The rotor supporting the pistons rotates around a first axis of rotation. The drum plates rotate in angled relation to the first axis. The rotor supporting the pistons is rotated in tandem with the drum plates during operation. Due to the angle between the rotor and the drum plates, the cups are caused to stroke along the length of the corresponding piston elements such that the volume occupied by the piston elements is alternately increased and decreased during the rotational cycle. Thus, fluid introduced into a cup element when the complementary piston is in a substantially withdrawn position may be pressurized and expelled as the cup is pushed inwardly during the rotational cycle. The reference discloses infinitely varying the displacement of the pump by varying the angle of a swashplate that is disposed axially outward of the drum plate between a zero angle and a maximum angle. However, the reference does not disclose providing the pump with a discrete set of displacement settings.

SUMMARY

The disclosure describes, in one aspect, a hydraulic motor. The hydraulic motor includes a rotor supporting a plurality of piston elements projecting away from opposing faces of the rotor. The rotor is adapted to rotate about a first axis. The hydraulic motor further includes a pair of drum plates each supporting a plurality of cup elements. The plurality of cup elements are adapted to engage the piston elements. Each drum plate is arranged on an opposing side of the rotor and is adapted to rotate about a second axis in angled relation to the first axis. Each of a pair of swashplates is in operative engagement with a respective one of the drum plates. Each swashplate is adapted to pivot relative to the rotor with the respective drum plate between a maximum displacement position and a minimum displacement position to thereby change the angled relation between the first axis and the second axis. The pair of swashplates are independently pivotable between a first setting in which both swashplates are in their maximum displacement position, a second setting in which both swashplates in their minimum displacement position and a third setting in which one swashplate is in its maximum displacement setting and the other swashplate is in its minimum displacement setting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cutaway schematic perspective view illustrating the components of an exemplary floating cup hydraulic motor.

DETAILED DESCRIPTION

This disclosure relates to a hydraulic motor. To allow for greater torque at start-up of the motor, the disclosed hydraulic motor is based on a floating cup pump. The hydraulic motor may be powered by any source of pressurized fluid such as, for example, a hydraulic pump. In different applications, it may be advantageous that the hydraulic motor be able to operate at different speeds.

FIG. 1 illustrates a motor 10 that is mounted within a motor housing 12. In this exemplary construction, an output shaft 14 extends along and is adapted for rotation about a first axis 16. The output shaft 14 is adapted for rotation around the first axis 16. The output shaft 14 engages a rotor 18 in the form of a disk or plate structure. Thus, rotation of the rotor 18 is translated to the output shaft 14 such that the rotor 18 rotates around the same axis as the output shaft 14, namely the first axis 16.

In the exemplary construction illustrated in FIG. 1, the rotor 18 supports an arrangement of piston elements 20 projecting away from opposing faces of the rotor 18 so as to define, in this case, left and right sides of the motor. As shown, the piston elements 20 may have a generally frusto-conical configuration such that the piston elements 20 taper outwardly as the distance increases away from rotor 18. However, other suitable constructions may likewise be utilized as desired.

In the illustrated construction of FIG. 1, the motor 10 includes a pair of drum plates 22 disposed on either side of the rotor 18 in each side of the motor 10. As shown, the drum plates 22 support an arrangement of cup elements 24 having open ends that project towards the rotor 18. The cup elements 24 are arranged to house distal portions of the complementary piston elements 20. With this configuration, the cup elements 24 circumferentially surround distal portions of the corresponding piston elements 20 such that the piston elements 20 cooperate with interior boundary walls of the cup elements 24 to define a plurality of variable volume piston chambers 25.

The drum plates 22 are arranged in circumferential relation to the output shaft 14 and are oriented at an angle relative to the rotor 18. Thus, the drum plates 22 and the cup elements 24 supported thereon are rotatable around axis lines disposed in angled relation to the first axis 16 of the output shaft 14 and rotor 18. According to the exemplary construction, the drum plates 22 are supported in this angled orientation by curved surface support elements 26 which are arranged around the output shaft 14 outboard from the rotor 18. The curved surface support elements 26 include a convex exterior support surface adapted to engage a portion of the drum plates 22. In the illustrated motor 10, a pair of swashplates 28 are provided with each being arranged outboard of and in operative engagement with a corresponding drum plate 22. In this case, each swashplate 28 is in contacting relation with its respective drum plate 22.

Although the motor 10 may be adapted for any number of uses, according to one contemplated practice, a high pressure fluid flows into the motor 10 through an intake port 30. Inside the motor 10, the power of the pressurized fluid is converted into mechanical energy in the form of rotation of the output shaft 14. The fluid then exits the motor through a discharge port 32 at a lower pressure. More specifically, as each piston element 20 and corresponding cup element 24 assembly passes over the intake port 30, the high pressure fluid enters the piston chamber 25 and causes the piston element 20 to extend outward relative to the corresponding cup element 24. The angle of the drum plate 22 relative to the piston element 20 displacement causes the rotor 18 and thereby the output shaft 14 to rotate. As a result of this rotation, each piston element 20 and cup element 24 assembly periodically passes over the intake and discharge ports 30, 32. Thus, the piston elements 20 undergo an oscillatory displacement in and out relative to their corresponding cup element 24 receiving high pressure fluid from the intake port 30 and discharging relatively lower pressure fluid through the discharge port 32.

During each rotation of the rotor 18, each piston element 20 displaces a certain distance in its corresponding cup element 24. The angle of the drum plate 22 relative to the rotor 18 and output shaft 14 determines the magnitude of the displacement of each piston element 20. In order to allow the displacement of the piston elements 20 to be varied, each swashplate 28, and with its corresponding drum plate 22, may be pivotable relative to the rotor 18 and output shaft 14 such that the angle of the swashplate 28 and drum plate 22 relative to the rotor 18 and output shaft 14, i.e. the first axis 16, can be changed. Varying the displacement of the piston elements 20 enables the speed and torque produced at the output shaft 14 of the motor 10 to be varied.

In this case, each swashplate 28 may be pivotable between a maximum displacement position in which the displacement of the piston elements 20 is maximized and a minimum displacement position in which the displacement of the piston elements 20 is minimized. Each of the swashplates 28 is shown in its maximum displacement position in FIG. 1. To reach the minimum displacement position, with reference to FIG. 1, the left swashplate 28 pivots clockwise and the right swashplate 28 pivots counter clockwise. The minimum displacement position can be any swashplate angle greater than a zero angle.

Each of the swashplates 28 may be independently pivotable with respect to the other swashplate. Accordingly, the disclosed motor 10 may operate at three different speed settings: A first low speed, high torque setting in which both swashplates 28 are in their maximum displacement position; a second high speed, low torque setting in which both swashplates 28 are in their minimum displacement position; and a third medium setting in which one swashplate 28 is in its minimum displacement position and one swashplate 28 is in its maximum displacement position. Providing three simple, discrete settings allows for greater flexibility for speed control than hydraulic motors that have only a single pivotable swashplate and are thus only capable of two operating speeds.

For pivoting the swashplates 28, the motor 10 may be equipped with an actuating system 34 that is adapted to independently pivot the swashplates 28 between their maximum and minimum displacement positions. In the illustrated motor 10, the actuating assembly 34 includes one or more actuators associated with each swashplate 28 that are operable in response to a control signal. In this case, a pair of actuators may be provided for each swashplate 28. In particular, a first actuator 36 acts on the inside face of the swashplate 28 near its lower edge and a second actuator 38 acts on the opposing outside face of the swashplate 28 near its upper edge. The actuating system 34 further includes a spring 40 that extends between the two swashplates 28 and operatively engages the upper edge of the inside face of each. The spring 40 acts to push the two swashplates 28 into their maximum displacement positions. Each of the first and second actuators 36, 38 may comprise a hydraulically actuated piston 42 and cup 44 assembly with the cups 44 disposed on the swashplates 28 and the pistons 42 disposed on the motor housing 12.

With the illustrated arrangement, the swashplates 28 may be pivoted into their respective minimum displacement positions by introducing a high pressure fluid into the cups 44 of each of the first and second actuators 36, 38. For each actuator 36, 38, the high pressure fluid pushes the cup 44 outward relative to the piston 42. Because the pistons 42 are fixed relative to the motor housing 12, this generates a forces at the lower edge of the inside face and the upper edge of the outside face of each swashplate 28 that together pivots the respective swashplate 28 against the force of the spring 40 to the minimum displacement position. Of course, actuators other than hydraulic actuators could be used including, for example, electrically actuated actuators. Additionally, the actuating system 34 could be configured such that the actuators 36, 38 pivot the swashplates 28 to the maximum displacement position and the spring 40 biases the swashplates 28 to the minimum displacement position. An actuating system that utilizes only a single actuator for each swashplate could also be used. Moreover, the actuators could comprise rotary devices configured to pivot the swashplates.

For independently actuating the actuators 36, 38 associated with each of the swashplates, the actuating system 34 may further include a control signal generator 46 that is operably coupled to the actuators 36, 38. The control signal generator 46 may be capable of providing separate control signals to the actuators 36, 38 associated with each of the swashplates 28. Upon receipt of the control signal, the respective actuators 36, 38 operate to pivot the swashplate 28 to the desired position. For example, with the illustrated motor 10, the control signal may be a supply of pressurized fluid that is supplied to the piston 42 and cup 44 assemblies of the corresponding actuators 36, 38. The pressurized fluid may be introduced to the motor 10 through separate first and second actuating ports 48, 50 that are provided in the motor housing 12. As shown in FIG. 1, in the illustrated motor, the first actuating port 48 is in fluid communication with the first and second actuators 36, 38 associated with the left swashplate while the second actuating port 50 is in fluid communication with the first and second actuators 36, 38 associated with the right swashplate 28. Because each swashplate is changing between only two discrete positions, the control signal generator can be relatively simple in that it only has to provide two signal types (i.e., an on/off type control) to each swashplate.

While the illustrated embodiment includes a single control signal generator 46, two separate control signal generators may be provided with each being associated with a respective one of the swashplates 28. Of course, if another type of actuator is used, such as electrical actuators, a corresponding control signal generator may be used such as a control signal generator that produces an electrical signal. Moreover, the control signal generator could be combined with a controller for the motor or integrated into the motor controller.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable to any type of machine that may utilize a hydraulic motor. For example, the present disclosure may be applicable to a track loader. On such a machine, a first hydraulic motor may be used to drive a right-side track and a second hydraulic motor may be used to drive a left-side track. As compared to conventional two-speed hydraulic motors, the disclosed hydraulic motor may offer an operator of the machine with additional flexibility with respect to speed control in that it may operate in three different speed settings. Additionally, the use of a floating cup arrangement may provide a higher initial starting torque than conventional piston pumps.

It will be appreciated that the foregoing description provides examples of the disclosed system and technique. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated.

Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.

Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context. 

1. A hydraulic motor comprising: a rotor supporting a plurality of piston elements projecting away from opposing faces of the rotor, the rotor being adapted to rotate about a first axis; a pair of drum plates each supporting a plurality of cup elements, the plurality of cup elements being adapted to engage the piston elements, each drum plate being arranged on an opposing side of the rotor and being adapted to rotate about a second axis in angled relation to the first axis; a pair of swashplates each being in operative engagement with a respective one of the drum plates, each swashplate being adapted to pivot relative to the rotor so as to move with the respective drum plate between a maximum displacement position and a minimum displacement position to thereby change the angled relation between the first axis and the second axis, wherein the pair of swashplates are independently pivotable between a first setting in which both swashplates are in their maximum displacement position, a second setting in which both swashplates in their minimum displacement position and a third setting in which one swashplate is in its maximum displacement setting and the other swashplate is in its minimum displacement setting.
 2. The hydraulic motor of claim 1 further including an output shaft connected to the rotor and extending along the first axis.
 3. The hydraulic motor of claim 2 further including an actuating system operable to independently pivot the pair of swashplates between the first setting, the second setting and the third setting.
 4. The hydraulic motor of claim 3 wherein the actuating system is hydraulically actuated.
 5. The hydraulic motor of claim 4 wherein the actuating system includes at least one actuator associated with each swashplate that is operable in response to a control signal to pivot the corresponding swashplate.
 6. The hydraulic motor of claim 5 wherein the actuating system further includes a control signal generator operably coupled to the at least one actuator associated with each swashplate for generating the control signal for the actuators.
 7. The hydraulic motor of claim 5 wherein the actuating assembly further includes a spring in operative engagement with both of the swashplates for biasing the swashplates toward one of their maximum displacement and minimum displacement positions.
 8. The hydraulic motor of claim 7 wherein the at least one actuator associated with each swashplate is operable to pivot the swashplates toward the other of their maximum displacement and minimum displacement positions.
 9. The hydraulic motor of claim 6 wherein the at least one actuator associated with each swashplate comprises a piston and cup assembly.
 10. The hydraulic motor of claim 6 wherein the control signal produced by the control signal generator comprises a supply of pressurized fluid.
 11. A hydraulic motor comprising: a rotor supporting a plurality of piston elements projecting away from opposing faces of the rotor, the rotor being adapted to rotate about a first axis; a pair of drum plates each supporting a plurality of cup elements, the plurality of cup elements being adapted to engage the piston elements, each drum plate being arranged on an opposing side of the rotor and being adapted to rotate about a second axis in angled relation to the first axis; a pair of swashplates each being in operative engagement with a respective one of the drum plates, each swashplate being adapted to pivot relative to the rotor so as to move with the respective drum plate between a maximum displacement position and a minimum displacement position to thereby change the angled relation between the first axis and the second axis; an actuating system operable to independent pivot the pair of swashplates between a first setting in which both swashplates are in their maximum displacement position, a second setting in which both swashplates in their minimum displacement position and a third setting in which one swashplate is in its maximum displacement setting and the other swashplate is in its minimum displacement setting.
 12. The hydraulic motor of claim 11 further including an output shaft connected to the rotor and extending along the first axis.
 13. The hydraulic motor of claim 11 wherein the actuating system is hydraulically actuated.
 14. The hydraulic motor of claim 11 wherein the actuating system includes at least one actuator associated with each swashplate that is operable in response to a control signal to pivot the corresponding swashplate.
 15. The hydraulic motor of claim 14 wherein the actuating system further includes a control signal generator operably coupled to the at least one actuator associated with each swashplate for generating the control signal for the actuators.
 16. The hydraulic motor of claim 15 wherein the actuating assembly further includes a spring in operative engagement with both of the swashplates for biasing the swashplates toward one of their maximum displacement and minimum displacement positions.
 17. The hydraulic motor of claim 16 wherein the at least one actuator associated with each swashplate is operable to pivot the swashplates toward the other of their maximum displacement and minimum displacement positions.
 18. The hydraulic motor of claim 14 wherein the at least one actuator associated with each swashplate comprises a piston and cup assembly.
 19. A method of operating a hydraulic motor comprising the steps of: introducing sequentially a fluid at an intake pressure into a plurality of cup elements supported on a pair of drum plates, the plurality of cup elements being adapted to engage a plurality of piston elements supported on a rotor with piston elements projecting away from opposing faces of the rotor which is adapted to rotate about a first axis, each drum plate being arranged on an opposing side of the rotor and being adapted to rotate about a second axis in angled relation to the first axis; discharging the fluid from the plurality of cup elements at a discharge pressure which is lower than the intake pressure; pivoting independently a pair of swashplates relative to the rotor between a maximum displacement position and a minimum displacement position, each swashplate being in operative engagement with a respective one of the drum plates such that each drum plate moves with the respective swashplate between the maximum and minimum displacement positions to thereby change the angled relation between the first and second axes; and selectively directing pivoting movement of the pair of swashplates into a first setting in which both swashplates are in their maximum displacement position, a second setting in which both swashplates in their minimum displacement position or a third setting in which one swashplate is in its maximum displacement setting and the other swashplate is in its minimum displacement setting.
 20. The method of claim 19 further including the step of transmitting rotation of the rotor to an output shaft that extends along the first axis. 